FWIW, I tend to do all my annual maintenance at the end of the season, and consider it part of winterizing the boat. The plugs, fuel filters, oil and oil filters are all changed out. Motors are lubed, including pulling the props and relubing the shafts and checking to make sure no fishing line is wrapped around the shaft behind the prop. The water system is drained, and I do pump RV antifreeze through it. Don't forget to drain your hot water heater if you have one. The 2.5 g bosch units some of us have gone with do not have a drain. Inside the tank, the cold water dip tube goes to almost the bottom of the tank, while the hot water dip tube only goes into the top of the tank. I blow the water out with a flushing valve on the hot water side. I open the cold spigot and blow air into the flushing valve on the hot side. Then once no more water is coming out, I pull the heating element and anode out, as they are usually full of corrosion. Soak them in vinegar and change the anode. (Rather than running more rv antifreeze into the water heater, I have it set up with some valves to shut the tank off from the rest of the water system, and with a valve that connects the cold and hot water lines.) While flushing the rv antifreeze thru the system, I also flush it into the shower drain to insure that the shower drain lines and pump are also winterized. I leave the engines trimmed down so that all water drains out of them. Also if storing the boat outside, I bag the props just to keep any critters from crawling in. Also keeps the snow out. I put bounce fabric sheets all through out the cabin, and the cockpit. (I have a full cover on the boat, even though this year I finally have a large storage unit I'm keeping it in.) Make sure you get the ones with the regular aroma and not the non-smelly ones. They work. I used them in a prior RV as well. This year in the storage unit, I do not have access to AC power, but in past years with the boat stored in my back yard, I kept it plugged in and had a small dehumidifying fan I ran. I still use the damprid stuff. I put rubber corks in all the thru holes, except for the bilge drain (so any water can still drain out) and the anchor locker drain (to small for a cork) I put scotch bright pads. I make sure everything is dry under the cushions, and just leave them in the boat. Also leave the batteries in, and just top them off with a charge when necessary. (This year in the storage unit, I'll either run the generator for the day, or bring the boat home and plug it in. Just easlier than pulling the batteries in and out.) I completely drain my fuel tank. (With the 25, it's a 100 g tank and I'd rather not leave that much fuel in it over winter. I have a small electric pump I can hook up at the main fuel filter to pull fuel out of the tank.) However, I will run stabilizer through the fuel with the last fill up to make sure any fuel in the lines and outboards is treated. I also run non-ethanol fuel thru the lines and motor before storage, as during the season, I burn the 10% regular.) I do use fogging oil in the outboards, but not sure it's really necessary since it's only stored about 4 months.
Don't forget to maintain your trailer as well. Check all fastener and hardware. I have oil bath hubs, and usually at least change the hub oil and check the wheel bearing free play. If you have the grease hubs, good time to change the grease. Check the brakes and all lighting.
